Moving image display device and method for moving image display

ABSTRACT

The synthesizing circuit inputs signals representing the brightness coefficient K 2  and the brightness coefficient K 3  from the multiplexer, and inputs the overscanned frame image data D 1  in pixel units from the first latch circuit. When the start frame image read the third time and the after frame image read the first time are input simultaneously, the synthesizing circuit calculates the brightness coefficient K 2  for the brightness value of the pixels of the start frame image, and calculates the brightness coefficient K 3  for the brightness value of the pixel of the after frame image. Then, it synthesizes the pixels of the start frame image and the pixels of the after frame image for which the respective brightness coefficients were calculated, and generates the intermediate frame image data D 2.

CLAIM OF PRIORITY

The present application claims priority from Japanese applicationP2005-314217A filed on Oct. 28, 2005, the content of which is herebyincorporated by reference into this application.

BACKGROUND

1. Field of the Invention

The present invention relates to technology for displaying moving imagesby consecutively displaying a plurality of frame images, and morespecifically relates to technology for synthesizing a plurality of frameimages and generating an intermediate frame image.

2. Description of the Related Art

In the past, when displaying images on a moving image display devicesuch as a CRT, television or the like with a refresh rate of less than60 Hz, there were cases when flicker (blinking) occurred on the overallscreen. However, even when a sufficient refresh rate is secured, incases when displaying moving images such as when a moving object moveson the screen, there were cases when flicker occurred only in the movingobject part on the screen rather than on the overall screen. Hereafter,this kind of flicker is called “moving image flicker.” This kind ofphenomenon occurs frequently, for example, when displaying moving imagesthat move at a fixed speed such as a person, car, airplane or the likewithin the screen, or moving images when panning the video camera at afixed speed.

This kind of phenomenon is not limited to CRTs and televisions, but isalso seen in cases when displaying moving images on moving image displaydevices such as liquid crystal displays, plasma displays, projectors orthe like, on the display unit of a PDA, mobile phone or the like, or onthe screen in a movie theater or the like, and this was a problem commonto moving image display. There were cases when once the viewers becamebothered by the existence of the moving image flicker described above,they felt stress while viewing.

Regarding this kind of problem, for example in JP-A-04-302289, disclosedis technology for displaying moving images smoothly by dynamicallygenerating new intermediate frame images from two frame images tosuppress the unnaturalness of the movement when displaying moving imagesin a liquid crystal moving image display device or the like having anapproximately 100% light emitting time ratio. In specific terms, asshown in FIG. 2 of patent reference 1, if it is a video image for whicha round mark moves from left to right on the screen, by newly drawinground marks that are at two positions intermediate to the round markwithin the before and after frames, an intermediate frame image isgenerated.

Also, disclosed in JP-A-2001-296841 is technology that detects whetheran input video image is a moving image or a still image, and when amoving image is displayed, switches to the optimal display method formoving image display by taking action to double the field frequency orthe like.

However, with the prior art described above, because it is necessary togenerate a completely new intermediate frame from two frame images, thecalculation processing for this becomes huge, so it was difficult toimprove the moving image display speed. Also, to generate a completelynew intermediate frame, it is necessary to secure a large frame memorycapacity, and this became a factor in increasing costs. Also, whenswitching the display method with moving images and still images, therewas concern that smooth video image display would not be possible due tothe occurrence of a virtual image during switching of the display methodor the like.

SUMMARY

For one aspect of the present invention, the purpose is to suppressmoving image flicker using a method that is simpler than in the past,and that displays smooth moving images.

To address the problem noted above, the moving image display device ofthe present invention is constituted as follows. Specifically, it is

a moving image display device for displaying moving images byconsecutively displaying a plurality of frame images, comprising:

input unit that inputs moving images for which a plurality of frameimages are recorded at a specified frame rate;

reading unit that reads from the input moving image a consecutivelydisplayed first frame image and second frame image;

brightness adjustment unit that performs brightness reduction processingto reduce the brightness based on a specified standard for at least oneof the first frame image and the second frame image;

synthesis unit that generates one or more intermediate frame images bysynthesizing the first frame image and the second frame image afterexecuting the brightness reduction process; and

display unit that displays the intermediate frame image beforedisplaying the second frame image after displaying the first frameimage, when displaying a moving image by displaying the first and secondframe images.

With the moving image display device of the present invention, it ispossible to generate an intermediate frame image by a very simpleprocess of performing simple synthesis while adjusting the respectivebrightness of the consecutively displayed first frame image and secondframe image, so it is possible to improve the processing speed. As aresult, even when the frame rate is improved from the original movingimage, it is easy to have the synthesizing process or the like followthat frame rate, and it becomes possible to suppress moving imageflicker and to perform smooth moving image display.

Also, with the present invention, because intermediate frame images aregenerated using a very simple process of simply synthesizing the firstframe image and the second frame image while adjusting their brightness,it is not necessary to generate a completely new intermediate frame.Therefore, it is possible to very simply constitute the hardware forperforming this processing, and it is also possible to reduce the usedmemory capacity. Because of this, it is possible to provide a movingimage display device for performing smooth moving image display whileattempting to keep costs down.

Also, the present invention can also be used as a moving image displaymethod, a program product for realizing that method on a computer, or arecording medium on which that program is recorded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the hardware constitution of theprojector 100.

FIG. 2 is a block diagram showing the detailed constitution of theintermediate frame generating circuit 140.

FIG. 3 is an explanatory drawing showing an example of the brightnesscoefficient table.

FIG. 4 is an explanatory drawing showing in simple form a timing chartof the operation of the intermediate frame generating circuit 140.

FIG. 5 is an explanatory drawing visually expressing the moving imageformed on the liquid crystal panel 180 according to the frame image dataoutput by the intermediate frame generating circuit 140.

FIG. 6 is an explanatory drawing showing the effect of the embodiment.

FIG. 7 is an explanatory drawing visually expressing the moving imageformed on the liquid crystal panel 180 of the second embodiment.

FIG. 8 is a drawing showing a table on which are defined values obtainedby dividing the space from 0 to π using the number of intermediate frameimages.

FIG. 9 is a drawing on which are graphed the functions used for thedetermination of the brightness coefficients.

FIG. 10 is a drawing showing a specific example of the values of thebrightness coefficient K2 and the brightness coefficient K3corresponding to the angle θ.

FIG. 11 is a drawing on which are graphed the functions for which thebrightness coefficient K3 increases linearly from 0 to 1 and thebrightness coefficient K2 decreases linearly from 1 to 0.

FIG. 12 is an explanatory drawing showing an example of generating theintermediate frame image with modification 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Following, to make even more clear the operation and effect of thepresent invention described above, a description is given in thefollowing sequence based on embodiments of the aspects of the presentinvention.

A. First Embodiment:

(A-1) Projector Hardware Constitution:

(A-2) Constitution and Operation of the Intermediate Frame GeneratingCircuit:

(A-3) Effect:

B. Second Embodiment:

C. Modification:

A. First Embodiment (A-1) Projector Hardware Constitution

FIG. 1 is a block diagram showing the hardware constitution of theprojector 100 as an embodiment of the moving image display device of thepresent invention. This projector 100 has a function of performingdisplay of moving images by increasing by at least two times the framerate of the original moving image. A detailed description will be givenlater regarding the specific constitution for performing display at twoor more times the frame rate.

As shown in the drawing, the projector 100 of the present inventioncomprises a video signal input circuit 110, a memory write controlcircuit 120 connected to this video signal input circuit 110, a framememory 130 connected to the memory write control circuit 120, a movingvector volume detection circuit 150 connected to the frame memory 130,the intermediate frame generating circuit 140 connected to the framememory 130 and the moving vector volume detection circuit 150, anenlargement and reduction circuit 160 connected to the intermediateframe generating circuit 140, a liquid crystal driver 170 connected tothe enlargement and reduction circuit 160, a liquid crystal panel 180connected to the liquid crystal driver 170, a CPU 190 connected to thememory write control circuit 120, the intermediate frame generatingcircuit 140, the enlargement and reduction circuit 160, and the liquidcrystal driver 170, and an operating panel 200 connected to the CPU 190.

The video signal input circuit 110 is a circuit for inputting videosignals such as composite signals or S video signals from externaldevices such as a DVD player, video deck, personal computer or the like,and component signals or the like. These video signals are typicallyanalog signals constituted from 1 to 30 frame images. The video signalinput circuit 110 comprises a sync separation circuit 112 and an A/Dconversion circuit 114.

The sync separation circuit 112 is a circuit that separatessynchronization signals of the vertical synchronization signals VSync orhorizontal synchronization signals HSync or the like from the inputvideo signal. The sync separation circuit 112 also performs generationof a dot clock DCK using a PLL circuit or the like according to thesynchronization of the vertical synchronization signals VSync or thehorizontal synchronization signals HSync for which separation wasperformed. Note that when video signals for which synchronous signalsare separated in advance are input, it is also possible to omit the syncseparation circuit 112.

The A/D conversion circuit 114 is a circuit that converts thesynchronous signal separated analog video signals to digital videosignals. When the A/D conversion circuit 114 generates the digital videosignal, this digital video signal is output to the memory write controlcircuit 120.

The memory write control circuit 120 writes the digital video signalsinput from the video signal input circuit 110 to the frame memory 130for each frame. Two frames of write area are secured in the frame memory140 (“area A” and “area B” in the drawing), and the memory write controlcircuit 120 writes the frame images alternately to these areas. Notethat with this embodiment, two write areas are comprised, but it is alsopossible to comprise three or more write areas and to performing writingin sequence to these areas.

The moving vector volume detection circuit 150 is a circuit that detectsthe moving vector volume V of a moving object imaged within these frameimages by comparing two frame images written in the frame memory 130.The moving vector volume V can be obtained by dividing the two frameimages respectively into a plurality of blocks, and by detecting thechange in brightness of each block common to both frame images. Thedetection of that moving vector volume can apply the known technologynoted in JP-A-2003-69961, for example.

The intermediate frame generating circuit 140 generates intermediateframe image data by reading the two frame image data from the framememory 130 and by synthesizing these while adjusting the brightness ofthese frame image data. The detailed constitution and operation of thisintermediate frame generating circuit 140 is described later. When theintermediate frame image data is generated, the intermediate framegenerating circuit 140 outputs to the enlargement and reduction circuit160 this intermediate frame image data and the frame image data readfrom the frame memory 130.

The enlargement and reduction circuit 160 is a circuit that enlarges orreduces the frame image data input from the intermediate framegenerating circuit 140 so as to match the resolution of the liquidcrystal panel 180. Note that the enlargement/reduction of the frameimage data can be performed when the memory write control circuit 120writes the frame image to the frame memory 130, or can also be performedwhen the intermediate frame generating circuit 140 reads the frame imagefrom the frame memory 130. In this case, it is possible to omit theenlargement and reduction circuit 160.

The liquid crystal driver 170 is a circuit that inputs the frame imagedata from the enlargement and reduction circuit 160 and drives theliquid crystal panel 180 according to that RGB gradation value.

The liquid crystal panel 180 is driven by the liquid crystal driver 170,and performs output image formation. The output image formed by theliquid crystal panel 180 is displayed by projection onto a projectionscreen by an optical system that is not illustrated.

The CPU 190 receives from the user using the operating panel 200 thesynthesis mode (described later) or various setting operations whengenerating the intermediate frame, and performs control of the memorywrite control circuit 120, the intermediate frame generating circuit140, the enlargement and reduction circuit 160, and the liquid crystaldriver 170 according to these settings.

(A-2) Constitution and Operation of the Intermediate Frame GeneratingCircuit

FIG. 2 is a block diagram showing the detailed constitution of theintermediate frame generating circuit 140. As shown in the drawing, thisintermediate frame generating circuit 140 comprises a brightnesscoefficient determining circuit 210 connected to the moving vectorvolume detection circuit 150, a multiplexer 220 connected to thisbrightness coefficient determining circuit 210, a first latch circuit272 connected to the frame memory 130, a synthesizing circuit 230connected to the multiplexer 220 and the first latch circuit 272, asecond latch circuit 274 connected to the synthesizing circuit 230, athird latch circuit 276 connected to the first latch circuit 272, and aselection circuit 240 connected to the second latch circuit 274 and thethird latch circuit 276. Furthermore, the intermediate frame generatingcircuit 140 comprises a control circuit 250, connected to the videosignal input circuit 110, for controlling each circuit described above,and a field identification signal generating circuit 260.

The field identification signal generating circuit 260 inputs thehorizontal synchronous signals HSync and the vertical synchronoussignals VSync from the video signal input circuit 110 to generate fieldidentification signals from these synchronous signals. The fieldidentification signal is a signal for identifying whether the field tobe displayed is an even numbered field or an odd numbered field for theinterlace display method. When a field identification signal isgenerated, the field identification signal generating circuit 260outputs that field identification signal to the control circuit 250.

The control circuit 250 inputs the horizontal synchronous signals HSync,the vertical synchronous signals VSync, and the dot clock DCK from thevideo signal input circuit 110, and also inputs the field identificationsignals from the field identification signal generating circuit 260, andbased on these signals, reads the frame image data from the frame memory130, and controls the operations of the first latch circuit 272, thesecond latch circuit 274, the third latch circuit 276, the multiplexer220, the synthesizing circuit 230, and the selection circuit 240.

The control circuit 250 consecutively reads three times respectively theframe image data to be displayed at the start (hereafter called “startframe image”) and the frame image data to be displayed after (hereaftercalled “after frame image”) from the frame memory 130 internal area Aand area B at twice the cycle of the original image frame rate(hereafter this kind of read is called “overscan”). At this time, byalternately reading for each pixel the third time start frame image andthe first time after frame image, synchronous reading is performed (seethe middle level in FIG. 5). From frame memory 130, it is possible toperform reading from each area using the burst mode. The frame imagedata overscanned in this way is held in pixel units by the first latchcircuit 272. The first latch circuit 272 branches the frame image dataD1 that holds the frame memory 130 internal areas A and B and outputsthem to the synthesizing circuit 230 and the third latch circuit 276.The third latch circuit 276, of the frame image data D1 output from thefirst latch circuit 272, holds as the frame image data D3 only the dataof the start frame image read the second time of three times.

The brightness coefficient determining circuit 210 determines thebrightness coefficient K2 and the brightness coefficient K3 valuesaccording to the synthesis mode set by the CPU 190, and outputs signalsrepresenting these values to the synthesizing circuit 230. Thebrightness coefficient K2 is a parameter for adjusting the brightness ofthe start frame image that is the generating source of the intermediateframe image, and the brightness coefficient K3 is a parameter foradjusting the brightness of the after frame image that is the generatingsource of the intermediate frame image.

As the synthesis modes set by the CPU 190, there are the fixed mode andthe variable mode. The fixed mode is a mode for which the brightnesscoefficient K2 and the brightness coefficient K3 are fixed to a constantvalue with no relation to the moving vector volume V. For this fixedmode, there are the “before and after equal mode” for which thebrightness coefficient K2 and the brightness coefficient K3 are each 1,and there is no change between the start frame image and the after frameimage brightness, the “before and after equal relaxation mode” for whichthe brightness coefficient K2 and the brightness coefficient K3 arecommon fixed values less than 1 (e.g. 0.7), the “after frame prioritymode” for which the brightness of the after frame image is higher thanthat of the start frame image, the “before frame priority mode” forwhich the brightness of the start frame image is higher than that of theafter frame image, and the like.

With the “before and after equal mode” and the “before and afterrelaxation mode,” it is possible to make the brightness coefficientcalculated for the start frame image and the after frame image the samevalue, so it is possible to try to simplify the processing. Also, withthe “after frame priority mode,” it is possible to generate anintermediate frame image for which the effect level of the after frameimage is higher than that of the start frame image. In contrast to this,with the “before frame priority mode,” it is possible to generate anintermediate frame image for which the effect level of the start frameimage is higher than that of the after frame image.

In contrast to the fixed mode described above, the variable mode is amode for which the brightness coefficient K2 and the brightnesscoefficient K3 values are varied according to the moving vector volume Vinput from the moving vector volume detection circuit 150. When thebrightness coefficient determining circuit 210 is set to this mode, thebrightness coefficient K2 and the brightness coefficient K3 aredetermined based on the brightness coefficient table shown in FIG. 3.

FIG. 3 is an explanatory drawing showing an example of the brightnesscoefficient table. In this brightness coefficient table, when the movingvector volume V is 0, specifically, when there is no movement betweenthe before and after frames, and when the moving vector volume V exceedsthe maximum visual limit value MHmax that human vision can follow,setting is done so that the brightness coefficient K2 and the brightnesscoefficient K3 are both 0.5. Also, when the moving vector volume V isgreater than 0 and smaller than the maximum visual limit value MHmax,the larger that the moving vector volume V becomes, setting is done sothat the brightness coefficient K3 is greater and the brightnesscoefficient K2 is smaller. Specifically, with this brightnesscoefficient table, in the normal moving vector volume V range, thegreater the moving vector volume V is, the stronger the reflection ofthe effect of the after frame image on the intermediate frame image.

The various synthesis modes described above can be selected freely bythe user according to the operation of the operating panel 200. The CPU190 accepts the selection of the synthesis mode by the user and sets theselected synthesis mode in the brightness coefficient determiningcircuit 210. By doing this, it is possible for the user to flexibly setthe synthesis mode suited to that moving image according to the purposeof the moving image display.

Note that when the projector 100 supports only the fixed mode, and doesnot support the variable mode, it is also possible to omit the movingvector volume detection circuit 150. By doing this, it is possible totry to simplify the process and to reduce costs. It is also possible tomake it possible for the user to freely set the value of the brightnesscoefficient used with the fixed mode described above.

The multiplexer 220 inputs signals that represent the brightnesscoefficient K2 and the brightness coefficient K3 from the brightnesscoefficient determining circuit 210, time-multiplexes these signals, andoutputs them to the synthesis circuit 230.

The synthesis circuit 230 inputs signals representing the brightnesscoefficient K2 and the brightness coefficient K3 from the multiplexer220, and also inputs overscanned frame image data D1 from the firstlatch circuit 272 in pixel units. When the start frame image and theafter frame image are input simultaneously from the first latch circuit272, specifically, when the start frame image read the third time andthe after frame image read the first time are input simultaneously, thesynthesis circuit 230 calculates the brightness coefficient K2 inrelation to the brightness value of the pixel of the start frame image,and calculates the brightness coefficient K3 in relation to thebrightness value of the pixel of the after frame image. Then, the pixelsof the start frame image and the pixels of the after frame image forwhich the respective brightness coefficients were calculated aresynthesized based on the formula (1) noted below, and the intermediateframe image data D2 is generated. When the intermediate frame image dataD2 is generated by the synthesis circuit 230, this intermediate frameimage data D2 is held by the second latch circuit 274.D2=(Start frame image D1*K2)+(After frame image D1*K3)  (1)

When the intermediate frame image data D2 held by the second latchcircuit 274 and the frame image data D3 held by the third latch circuit276 are input, the selection circuit 240 alternately selects two data atdoubled cycles of the original video image vertical synchronous signalVSync. Then, the selected frame image data is output to the enlargementand reduction circuit 160 as the frame image data D4. Note that from thecontrol circuit 250, the dot clock MDCK, horizontal synchronous signalsMHSync, and vertical synchronous signals MVSync necessary for displayingthe frame image data D4 on the liquid crystal panel 180 are output tothe enlargement and reduction circuit 160. In the case of thisembodiment, the vertical synchronous signal MVSync is at a doubled cycleof the vertical synchronous signal VSync input from the video signalinput circuit 110.

FIG. 4 is an explanatory drawing showing in simple form a timing chartof the operation of the intermediate frame generating circuit 140. Withthe intermediate frame generating circuit 140 described above, when thehorizontal synchronous signal HSync, the vertical synchronous signalVSync, and the dot clock DCK are input from the video signal inputcircuit 110, the field identification signal FS is generated from thesesynchronous signals. Then, from the intermediate frame generatingcircuit 140, as the finally output frame image data D4, with the eventiming which displays even numbered fields, the frame image data D3 (inthe drawing, D3 (n−1), D3 (n), D3 (n+1)) is output acquired as is fromthe original moving image, and with the odd timing which displays oddnumbered fields, the intermediate frame image data D2 (in the drawing,D2 (n−1), D2 (n), and D2 (n+1)) generated by the intermediate framegenerating circuit 140 is output.

FIG. 5 is an explanatory drawing visually expressing the moving imageformed on the liquid crystal panel 180 according to the frame image dataoutput by the intermediate frame generating circuit 140. Shown in thetop level of the drawing is the frame image data stored in the framememory 130, and shown in the middle level is the overscanned frame imagedata D1 from this frame memory. Also, shown at the lower level of thedrawing is the frame image data D4 output from the selection circuit240. For the frame image data D4 shown at the lower level of thedrawing, shared frame numbers with those of the frame image data D4 areallocated.

As shown in the upper level of the drawing, within the frame memory 130are stored in sequence the frame image data of frame (N−1), frame (N),and frame (N+1), and as shown in the middle section of the drawing,these frame images are overscanned by the control circuit 250, and eachframe respectively has three items each output. Note that forconvenience of illustration, for frame (N−1) and frame (N+1), among thethree items, output for two items is shown. Of the three frame imagesoverscanned in this way, for the second of the frame images, this isoutput as the frame image data D4 as is by the selection circuit 240. Incontrast to this, for the third of the start frame images and the firstof the after frame images, the brightness coefficients K2 and K3 arecalculated and synthesized for the respective image brightness values bythe synthesizing circuit 230, and the intermediate frame image data D2is generated. Then, this intermediate frame image data D2 is selected bythe selection circuit 240, and is output as the frame image data D4. Asa result, as shown in the lower level of the drawing, as shown by D3,D2, D3, D2, . . . , the frame image data D3 that constituted theoriginal moving image and the intermediate frame image data D2 generatedby the intermediate frame generating circuit 140 are alternately outputfrom the selection circuit 240, and that image is formed on the liquidcrystal panel 180.

With the example shown in FIG. 5, the moving vector volume V betweenframe (N−1) and frame N is 10. Because of this, for the intermediateframe image data D2 which is the synthesis result of frame (N−1) andframe (N), the brightness coefficients K2 and K3 are determinedaccording to this moving vector volume V and the brightness coefficienttable shown in FIG. 3, and as a result of this, an image is synthesizedfor which the respective frame image brightness values are decreased.Meanwhile, since the moving vector value V between the frame (N) andframe (N+1) is 0, according to FIG. 3, both brightness coefficients K2and K3 are 0.5, and the frame image D2 synthesized by these brightnesscoefficients ends up having the same contents as the original frameimage.

(A-3) Effect

FIG. 6 is an explanatory drawing showing the effect of the embodiment.Here, shown is an example for which a moving image is displayed where ablack circle graphic moves from left to right. At the left side of thedrawing, shown is an example of display when the intermediate frameimage is not generated, and at the right side of the drawing, shown isan example of display when the intermediate frame image is generated inaccordance with this embodiment. As shown at the right side of thedrawing, when the intermediate frame image is not generated, the blackcircle display state is nothing more than changing display/non-displayin two levels, so even when a suitable frame rate is secured, this isobserved as if moving is discontinuous when the black circle movingspeed is fast, and moving image flicker occurs. However, with thisembodiment, as shown at the right side of the drawing, becauseintermediate frame images synthesized with adjustment of the brightnessof the before and after frames are inserted between the frame imagesthat constitute the original moving image, the black circles areobserved as moving smoothly. Because of this, moving image flicker isreduced, so it is possible to reduce the burden of the user viewing.

Also, with this embodiment, because intermediate frame images aregenerated using a very simple process of simple synthesis whilerespectively adjusting the brightness of the start frame image and theafter frame image, it is possible to improve the processing speed. As aresult, even when the frame rate is increased by 2 or more times fromthe original moving image, having the synthesis process or the likefollow that frame rate becomes easy, and it becomes possible to performsmooth display of moving images.

Also, with this embodiment, as described above, because the intermediateframe images are generated using a very simple process of simplesynthesis while respectively adjusting the brightness of the start frameimage and the after frame image, it is not necessary to generate acompletely new intermediate frame image. Therefore, it is possible toconstitute the digital circuit for performing this processing verysimply, and also possible to reduce the used memory capacity. Because ofthis, it is possible to provide a projector capable of performing smoothmoving image display while attempting to reduce costs.

Also, with this embodiment, even when there is switching between movingimages and still images within the same video image, it is possible togenerate the intermediate frame images using the same circuit andalgorithm, suppressing the occurrence of moving image flicker for onlythe moving image. Because of this, it is not necessary to prepare twocircuits, one for displaying moving images and one for displaying stillimages, or to perform the process of switching between these, so it ispossible to constitute a circuit simply. This kind of effect isespecially marked when performing output using the fixed mode whileomitting the moving vector volume detection circuit 150 or the like.

B. Second Embodiment

With the first embodiment described above, described was a case when oneintermediate frame image was generated and display of the moving imagewas performed at twice the frame rate of the original video image. Incontrast to this, with the second embodiment, described is a case whentwo intermediate frame images are generated, and the moving image isdisplayed at a frame rate that is three times that of the original videoimage.

FIG. 7 is an explanatory drawing visually expressing the moving imageformed on the liquid crystal panel 180 of the second embodiment. Asshown in the upper level and middle level of the drawing, with thisembodiment, the memory write control circuit 120 writes in sequence tothe frame memory 130 the frame image data frame (N−1), frame (N), andframe (N+1), and the control circuit 250 performs five consecutivereadings at a doubled cycle of the frame rate of the original videoimage. At this time, simultaneous reading is performed by alternatelyreading respectively for each pixel the fourth start frame image and thefirst after frame image, and the fifth start frame image and the secondafter frame image. As a result, as shown at the lower level of thedrawing, of the five items for which overscan was performed, for threeframe images, these are output as is as the frame image data D4 by theselection circuit 240. In contrast to this, for the fourth start frameimage and first after frame image, and the fifth start frame image andsecond after frame image described above, the brightness coefficients K2and K3 are calculated for the respective image brightness values by thesynthesis circuit 230 and then synthesized, and the intermediate frameimage data D2 is generated. Then, this intermediate frame image data D2is selected by the selection circuit, and is output as the frame imagedata D4.

With the example shown in FIG. 7, the brightness coefficient K2 and thebrightness coefficient K3 values are calculated at respectivelydifferent combinations with the first intermediate frame image data D2and the second intermediate frame image data D2 of the two consecutivelygenerated intermediate frame image data D2. In specific terms, with thefirst intermediate frame image, the brightness coefficient K2 is 0.7 andthe brightness coefficient K3 is 0.3, and with the second intermediateframe image, the brightness coefficient K2 is 0.3 and the brightnesscoefficient K3 is 0.7. By working in this way, there is a gradualdecrease in the brightness of the start frame image, and a gradualincrease in the brightness of the after frame image, and it is possibleto obtain an effect of the moving object gradually moving.

Note that with FIG. 7, shown is an example with the values of brightnesscoefficients K2 and K3 respectively fixed, but, for example, it is alsopossible to determine the values of the brightness coefficient K2 andthe brightness coefficient K3 using the brightness coefficient tableshown in FIG. 3 for the first intermediate frame image, and to determinethe values of the brightness coefficients by interchanging the values ofthe first [frame] brightness coefficient K2 and the brightnesscoefficient K3 for the second intermediate frame image. It is alsopossible to individually prepare a table for determining the first[frame] brightness coefficients K2 and K3 and a table for determiningthe second [frame] brightness coefficients K2 and K3.

Because with the second embodiment described above, it is possible togenerate and display more intermediate frame images than with the firstembodiment, it is possible to further suppress the occurrence of movingimage flicker. Note that with this embodiment, described was a case ofgenerating two intermediate frame images, but it is also possible to usethe same method by respectively determining the brightness coefficientsK2 and K3 for each intermediate frame image even when generating threeor more intermediate frame images. In this case, display of each frameimage is performed by multiplying the frame rate of the original videoimage by a multiple according to the number of intermediate frameimages. If the number of intermediate frame image is increased, it ispossible to increase the effect of decreasing the moving image flickerby a corresponding amount.

C. Modifications

Above, various embodiments of the present invention were described, butthe present invention is not limited to these embodiments, and it goeswithout saying that various constitutions can be used within a scopethat does not stray from its key points. For example, it is alsopossible to have this be an item for which the moving images aredisplayed by a computer by realizing using software the functions thatwere realized by hardware. In addition, the following kinds ofvariations are also possible.

(C-1) Modification 1

Following, using FIG. 8 through FIG. 10, described is a modification ofthe method of determining the brightness coefficients K2 and K3. Withthis modification, the brightness coefficient determining circuit 210shown in FIG. 2 determines the values of the brightness coefficients K2and K3 according to the number n of intermediate frame images to begenerated and the sine wave characteristics, with no relation to themoving vector volume V.

With this modification, when the number of intermediate frame images forwhich to perform generation using the synthesizing circuit 230 is setfrom the CPU 190, the brightness coefficient determining circuit 210determines the angle θ (rd) (0<θ<π) for obtaining the brightnesscoefficient K2 and K3 for each intermediate frame image based on thetable shown in FIG. 8. The values obtained by dividing the space from 0to π by the number of intermediate frame images are defined in the tableshown in FIG. 8. According to this table, for example when generatingthree intermediate frame images, the θ for generating the firstintermediate frame image is (¼) π, the second is (½) π, and the third is(¾) π. Then, as the value of this θ, using the sine function shown inthe following formulas (2) and (3), the respective brightnesscoefficients K2 and K3 used for generating each intermediate frame imageare determined. Formula (2) below is a function representing from thesine function maximum value (=1) to the minimum value (=0), and formula(3) is the function representing from the sine function minimum value(=0) to the maximum value (=1). FIG. 9 shows a graphed image of thefollowing functions, and FIG. 10 shows specific examples of the valuesof the brightness coefficient K2 and the brightness coefficient K3corresponding to the angle θ.K2=(COS θ)/2+0.5  (2)K3=0.5−(COS θ)/2  (3)

Referring to FIG. 10, according to the functions (2) and (3) notedabove, when generating three intermediate frame images, the brightnesscoefficient K2 used for the first intermediate frame image is 0.85 andthe brightness coefficient K3 is 0.15. Also, the brightness coefficientK2 used for the second intermediate frame image is 0.50 and thebrightness coefficient K3 is 0.50. Furthermore, the brightnesscoefficient K2 used for the third intermediate frame image is 0.15 andthe brightness coefficient K3 is 0.85.

With the method of determining the brightness coefficient describedabove, it is possible to determine the brightness coefficient used foreach intermediate frame image according to the wave characteristics ofthe sine wave. The brightness change following characteristics of thehuman eye are thought to approximate this sine wave characteristic, andwith this modification, even when the number of intermediate frameimages is increased, the moving image brightness change is very smooth,and it is possible to effectively suppress the moving image flicker.

Note that with this modification the brightness coefficients were foundusing the sine function, but in addition to this, it is also possible tofind the brightness coefficients using various functions that graduallyincrease or gradually decrease. FIG. 11 shows an example of this kind offunction.

FIG. 11 is a drawing on which are graphed the functions for which thebrightness coefficient K3 increases linearly from 0 to 1 and thebrightness coefficient K2 decreases linearly from 1 to 0. Even with thiskind of function, it is possible to obtain an effect of having theeffect of the start frame image gradually decrease, and having theeffect of the after frame image gradually increase, so it is possible toperform smooth moving image display.

Note that with this modification, the functions shown in FIG. 9 and FIG.11 are functions for which the value when the brightness coefficient K2and the brightness coefficient K3 are added is always 1. Because ofthis, it is possible to reduce the moving image flicker withoutdecreasing the brightness of the intermediate frame image in relation tothe normal frame image.

(C-2) Modification 2

With the embodiment noted above, shown was an example of determining thebrightness coefficients K2 and K3 according to the moving vector volumebetween the two frame images stored in the frame memory 130. In contrastto this, it is also possible to determine the brightness coefficients K2and K3 according to the volume of change in brightness of the two frameimages.

In this case, for example, the brightness coefficient determiningcircuit 210 first finds the average value of the brightness of eachpixel that constitutes the start frame image, and the average value ofthe brightness of each pixel that constitutes the after frame image, andthen the change volume of the brightness is found from these averagevalues. Then, if this change volume is in the plus direction, the valueof the brightness coefficient K2 calculated for the start frame image islower than the brightness coefficient K3 calculated for the after frameimage according to this change volume. On the other hand, if it is inthe minus direction, it is possible to have the value of the brightnesscoefficient K2 calculated for the start frame image be higher than thebrightness coefficient K3 calculated for the after frame image accordingto this change volume. Even with this kind of modification, it ispossible to display moving images smoothly.

(C-3) Modification 3

With the embodiment noted above, shown was an example for which themoving image display device of this application was constituted as theprojector 100, but it is also possible to constitute the moving imagedisplay device as a liquid crystal display, a CRT display, a plasmadisplay or the like. In this case, the liquid crystal driver 170 and theliquid crystal panel 180 shown in FIG. 1 are items that can be replacedwith drive circuits or display devices suited to each display device. Itis also possible to vary the brightness coefficient according to thevarious types of these display devices.

(C-4) Modification 4

With the embodiment described above, when generating the intermediateframe image, the intermediate frame image was generated by adjusting thebrightness value of the before and after frames. In contrast to this,for example, it is also possible to generate intermediate frame imagesby adjusting the hue or color, or any of the values among the R, G, andB values. Of course, it is also possible to perform adjustment withthese parameters combined.

(C-5) Modification 5

With the embodiment described above, reading of images from the framememory 130 by the control circuit 250 or brightness adjustment andsynthesis of images by the synthesizing circuit 230 were described asbeing performed in pixel units. However, the units for performing theseprocesses do not have to be pixel units, but performance can also bedone using frame units, line units, or scan line units. It is possibleto determine which unit to perform processes with according to the datacapacity that can be held by each latch circuit or the buffer capacitywithin the synthesizing circuit 230.

(C-6) Modification 6

With the second embodiment described above, shown was an example ofgenerating two intermediate frame images. In contrast to this, with thismodification, display is performed with the brightness of oneintermediate frame image among the plurality of generated intermediateframe images decreased to be lower than that of the other intermediateframe images.

FIG. 12 is an explanatory drawing showing an example of generating theintermediate frame image with this modification. With the example shownin the drawing, three intermediate frame images are generated, and amongthese, for one of the intermediate [frame images], both the brightnesscoefficient K2 used for the start frame image and the brightnesscoefficient K3 used for the after frame image are 0.1, and the sum totalvalue of these is less than 1. In this way, if an intermediate frameimage that uses low brightness coefficients is generated, a mask imagethat is darker than the other frame images is displayed at a fixedtiming. In this way, if a dark mask image is displayed at regularcycles, it is possible to suppress the residual image phenomenonspecific to hold type display devices such as liquid crystal panels orthe like.

Note that with this modification, by using low brightness coefficientsfor both the start frame image and the after frame image, a darkintermediate frame image was generated. In contrast to this, with thetiming of displaying one intermediate frame image of the plurality ofintermediate frame images, it is also possible to change to thatintermediate frame image, and to insert a specified mask image to lowerthe brightness to make a black image for display. As this kind of maskimage, it is possible to prepare in advance images made only from lowbrightness pixels such as black color. The device for inserting the maskimage can be the synthesizing circuit 230 or can be the selectioncircuit 240 or the enlargement and reduction circuit 160. Even with thiskind of constitution, it is possible to easily suppress the residualimage phenomenon. Also, with FIG. 12, three intermediate frame imagesare generated, and of these, one is a dark image, but it is alsopossible to have one be a dark image as long as there are two or moreintermediate frame images generated.

For the embodiments of the moving image display device of the presentinvention, we described these together with modifications, but it isalso possible to use the following constitutions as aspects of themoving image display device of the present invention.

As one aspect of the moving image display device of the presentinvention, it is possible to realize an item for performing theaforementioned brightness reduction process by respectively calculatingthe first brightness coefficient of 0 or greater but less than 1 for thebrightness value of the first frame image for the brightness adjustmentunit, and a second brightness coefficient of 0 or greater and less than1 for the brightness value of the second frame image. With this kind ofconstitution, it is possible to easily adjust the brightness of eachframe image by using the brightness coefficients.

In this case, the first brightness coefficient and the second brightnesscoefficient can be the same value. With such a constitution, it is notnecessary to individually determine brightness coefficients for thefirst frame image and the second frame image, so it is possible tosimplify the processing.

As another aspect, it is conceivable to have the first brightnesscoefficient be a larger value than the second brightness coefficient forthe brightness adjustment unit. With such a constitution, it is possibleto make the brightness of the first frame image higher than thebrightness of the second frame image, so it is possible to generate anintermediate frame image for which the effect of the first frame imagethat is displayed first in terms of time is heightened.

Alternatively, it is also possible to have the first brightnesscoefficient be a smaller value than the second brightness coefficientfor the brightness adjustment unit. By doing this, it is possible tohave the brightness of the first frame image be lower than thebrightness of the second frame image, so it is possible to generate anintermediate frame image for which the effect of the second frame imagewhich is displayed afterwards in terms of time is heightened.

As another aspect of the moving image display device, it is furtherpossible to have a moving vector volume detection unit that finds themoving vector volume of the moving object imaged within these frameimages from the first frame image and the second frame image, and forthe brightness adjustment unit, to determine the first brightnesscoefficient and the second brightness coefficient according to themoving vector volume. With this constitution, it is possible todetermine the brightness coefficient according to the movement vectorvolume between the two frame images, so it is possible to performsmoother moving image display.

Alternatively, it is also possible to constitute the brightnessadjustment unit as one that determines the first brightness coefficientand the second brightness coefficient based on the table for which therelationship of the first and second brightness coefficients ispredefined. With this kind of constitution, it is possible to determinethe brightness coefficient according to the moving vector volume simplybe referencing the table, so it is possible to increase the processingspeed.

Furthermore, it is also possible to have this be equipped with abrightness change volume detection unit that finds from the first frameimage and the second frame image the change volume of the brightnessbetween these frame images, and to have an item that determines thefirst brightness coefficient and the second brightness coefficientaccording to the brightness change volume. With this constitution, it ispossible to determine the brightness coefficient according to thebrightness change volume between the two frame images, so it is possibleto perform smoother moving image display.

Alternatively, it is also possible to have the brightness adjustmentunit respectively determine the first brightness coefficient and thesecond brightness coefficient for generating each intermediate frameimage according to the number of intermediate frame images generated bythe synthesizing unit. By doing this, it is possible to calculate eachbrightness coefficient individually for the plurality of generatedintermediate frame images, so it is possible to perform smoother movingimage display.

As another aspect of the moving image display device, it is possible togenerate two or more intermediate frame images, and with the brightnessadjustment unit, for the intermediate frame images displayed on thefirst frame image side, to perform the aforementioned brightnessreduction processing with the first brightness coefficient at a valuegreater than that of the second brightness coefficient, and for theintermediate frame images displayed at the second frame image side, toperform the brightness reduction processing with the first brightnesscoefficient at a value lower than that of the second brightnesscoefficient. With this constitution, it is possible to generate anintermediate frame image for which the brightness of the first frameimage gradually decreases while the brightness of the second frame imagegradually increases, so it is possible to perform smoother moving imagedisplay.

Furthermore, for the brightness adjustment unit, it is also possible toprepare a first function that gradually increases from 0 to 1 in adesignated space and a second function that gradually decreases from 1to 0, to divide this designated space according to the number ofintermediate frame images, and to determine the first brightnesscoefficient and the second brightness coefficient based on the values ofthe first and second functions at the division point. By doing this, itis possible to easily determine the brightness coefficients according tothe first function and the second function.

Here, the aforementioned first function and the aforementioned secondfunction for the brightness adjustment unit can be functions thatrepresent from the minimum value to the maximum value of the sinefunction. By doing this, it is possible to determine the brightnessfunction based on the function representing the sine wave thatapproximates the brightness change following characteristics of thehuman eye, so it is possible to perform smoother moving image display.

Also, as an aspect of implementing this moving image display device, itis also possible to perform the first frame image and the second frameimage read process, brightness reduction process, and synthesis processusing any units from among the frame image frame units, line units,pixel units, or scan line units. By doing this, it is possible togenerate the intermediate frame images using the optimal unit set takinginto account the frame memory capacity that the moving image displaydevice has or the like. Note that with the reading unit, the brightnessadjustment unit, and the synthesis unit, it is possible to perform eachprocess with the same respective units, or to perform each process withdifferent respective units.

Alternatively, it is also possible to perform display by multiplying theframe rate for the display unit according to the number of generatedintermediate frame images. By doing this, it is possible to performdisplay with a heightened frame rate of the moving image while insertingintermediate frame images, so it is possible to perform smoother movingimage display.

Also, as an aspect of the moving image display device, it is possible tohave the synthesis unit generate two or more intermediate frame images,and at the timing when the display unit displays one intermediate frameimage of the two or more intermediate frame images, to change to thisone intermediate frame image, and to perform display of a specified maskimage with low brightness. Note that as the mask image, it is possibleto have the total brightness coefficient be less than 1 and use an imagewith reduced brightness, or to use an image that was constituted inadvance using only low brightness pixels such as black color or thelike.

Furthermore, it is possible to have the synthesis unit generate two ormore intermediate frame images, and of the intermediate frame imagesgenerated by the synthesis unit, to have the total of the firstbrightness coefficient and the second brightness coefficient used forthe specified one intermediate frame image be less than 1.

Using these constitutions, when displaying a plurality of intermediateframe images, it is possible to display one of those intermediate frameimages as a low brightness mask image. Because of this, in addition tosuppressing moving image flicker, it is also possible to suppress theresidual image phenomenon specific to hold type display devices such asliquid crystal display panels and the like.

Note that in addition to being able to implement the present inventionas the moving image display device described above, it is also possibleto implement this as a moving image display method or a computerprogram. This computer program can also be recorded on a computerreadable recording medium. As the recording medium, for example, it ispossible to use various media such as a flexible disk, CD-ROM, DVD-ROM,optical magnetic disk, memory card, hard disk, or the like.

The present invention can be implemented with a variety of aspectswithin a scope that does not change its key points. The contents of thepresent invention are determined by its technical concept.

1. A moving image display device for displaying moving images bydisplaying in sequence a plurality of frame images, comprising thefollowing: input unit that inputs moving images on which a plurality offrame images are recorded at a specified frame rate; reading unit thatreads a first frame image and a second frame image displayedconsecutively from the input moving image; brightness adjustment unitthat performs the brightness reduction process of reducing thebrightness for at least any one of the first frame image and the secondframe image; synthesis unit that generates one or more intermediateframe images by synthesizing the first frame image and the second frameimage after executing the brightness reduction process; and display unitthat displays the intermediate frame after display of the first frameimage and before display of the second frame image, when displayingmoving images by displaying in sequence the plurality of frame imagesincluding the first and second frame images.
 2. A moving image displaydevice in accordance with claim 1, wherein for the brightness adjustmentunit, the brightness reduction process is performed by respectivelycalculating a first brightness coefficient of 0 or greater but less than1 for the brightness value of the first frame image, and a secondbrightness coefficient of 0 or greater but less than 1 for thebrightness value of the second frame image.
 3. A moving image displaydevice in accordance with claim 2, wherein the first brightnesscoefficient and the second brightness coefficient for the brightnessadjustment unit are the same value.
 4. A moving image display device inaccordance with claim 2, wherein the first brightness coefficient forthe brightness adjustment unit is a value larger than the secondbrightness coefficient.
 5. A moving image display device in accordancewith claim 2, wherein the first brightness coefficient for thebrightness adjustment unit is a value smaller than the second brightnesscoefficient.
 6. A moving image display device in accordance with claim2, further comprising a moving vector volume detection unit that findsfrom the first frame image and the second frame image moving vectorvolume of a moving object imaged within these frame images, the movingvector volume including a direction and a speed of the movement of themoving object; and wherein the brightness adjustment unit determines thefirst brightness coefficient and the second brightness coefficientaccording to the moving vector volume.
 7. A moving image display devicein accordance with claim 6, wherein the brightness adjustment unitdetermines the first brightness coefficient and the second brightnesscoefficient based on the moving vector volume and a table in which ispredefined the relationship of the first and second brightnesscoefficients.
 8. A moving image display device in accordance with claim2, further comprising a brightness change volume detection unit thatfinds brightness change volume between these frame images from the firstframe image and the second frame image, and wherein the brightnessadjustment unit determines the first brightness coefficient and thesecond brightness coefficient according to the brightness change volume.9. A moving image display, device in accordance with claim 2, whereinthe brightness adjustment unit respectively determines the firstbrightness coefficient and the second brightness coefficient forgenerating each intermediate frame image according to the number ofintermediate frame images generated by the synthesis unit.
 10. A movingimage display device in accordance with claim 9, wherein the synthesisunit generates two or more of the intermediate frame images, and thebrightness adjustment unit performs the brightness reduction processwith the first brightness coefficient as a larger value than the secondbrightness coefficient for the intermediate frame images displayed onthe first frame image side, and performs the brightness reductionprocess with the first brightness coefficient as a smaller value thanthe second brightness coefficient for the intermediate frame imagesdisplayed on the second frame image side.
 11. A moving image displaydevice in accordance with claim 9, wherein the brightness adjustmentunit prepares a first function that gradually increases from 0 to 1 in aspecified space, and a second function that gradually decreases from 1to 0, divides that specified space according to the number of theintermediate frame images, and determines the first brightnesscoefficient and the second brightness coefficient based on the value ofthe first and second functions at the division point.
 12. A moving imagedisplay device in accordance with claim 11, wherein the first functionand the second function for the brightness adjustment unit are functionsrepresenting from the minimum value to the maximum value of the sinefunction.
 13. A moving image display device in accordance with claim 2,wherein the synthesis unit generates two or more intermediate frameimages, and the brightness adjustment unit has the total of the firstbrightness coefficient and the second brightness coefficient used forthe specified one intermediate frame image of the intermediate frameimages generated by the synthesis unit be less than
 1. 14. A movingimage display device in accordance with claim 1, wherein any of theframe image read process, the brightness reduction process, and thesynthesis process of the first frame image and the second frame image isperformed using any one of the units among frame unit, the line unit,the pixel unit, and the scan line unit of the frame image.
 15. A movingimage display device in accordance with claim 1, wherein the displayunit performs the display with the frame rate multiplied according tothe number of the generated intermediate frame images.
 16. A movingimage display device in accordance with claim 1, wherein the synthesisunit generates two or more intermediate frame images, and the displayunit, at the timing of displaying one intermediate frame image of thetwo or more intermediate frame units, changes to that one intermediateframe image, and performs display of a specified mask image of lowbrightness.
 17. A moving image display method by which the moving imagedisplay device displays moving images by consecutively displaying aplurality of frame images, comprising: inputting of moving images onwhich are recorded a plurality of frame images at a specified framerate; reading of the consecutively displayed first frame image andsecond frame image from the input moving images; performing of thebrightness reduction process for reducing the brightness for at leastone of any of the first frame image and the second frame image;generating of one or more intermediate frame images by synthesizing thefirst frame image and the second frame image after executing thebrightness reduction process; and displaying of intermediate frame afterdisplay of the first frame image and before display of the second frameimage when displaying moving images by displaying the first and secondframe images.
 18. A computer program product for displaying movingimages by a computer consecutively displaying a plurality of frameimages, consisting of a computer program and a recording medium on whichthis is recorded; the computer program comprising: a first program codefor inputting moving images on which are recorded a plurality of frameimages at a specified frame rate; a second program code for reading theconsecutively displayed first frame image and second frame image fromthe input moving image; a third program code for performing thebrightness reduction process for reducing the brightness on at least oneof any of the first frame image or the second frame image; a fourthprogram code for generating one or more intermediate frame images bysynthesizing the first frame image and the second frame image after thebrightness reduction process is executed; and a fifth program code fordisplaying the intermediate frame image after display of the first frameimage and before display of the second frame image when displaying amoving image by displaying the first and second frame image.